Problem Solving Forum
August 7 - August 13, 2016
On a parking deck with harsh exposures—to road salt, frequent wetting, freeze-thaw cycles, and exterior weathering—what generic coating type works best, and why?
Joe Miller of NextGen Green Building Products, Inc. dba Direct2Contractors.com on
August 11, 2016:
Liquid applied, moisture-cured, elastomeric, 1-com ...read more Liquid applied, moisture-cured, elastomeric, 1-component polyurethane coatings are ideal for this type of service conditions---based on empirical data and successful performance on many such parking decks in all kinds of climate zones. They are durable and they have excellent chemical resistance and resistance to abrasion of vehicular traffic for many, many years. They are also recoatable, a feature that allows for reapplication in high traffic lanes, turns and ramps that may have been damaged by sudden stopping or turning of the vehicles over time. Moisture-cured polyurethane chemistry can be fine-tuned in several variations, including zero VOC and odor-free versions that can be used in places where they are beneficial to the environment and the people in the vicinity of the parking decks. The 1-component, moisture-cure polyurethane chemistry retains its performance properties so that waterproofing of the decks is assured despite the vehicular traffic loads as well as exposure to bright sunlight or freeze-thaw conditions.The polyurethane coatings can be seeded with aggregates to enhance their coefficient of friction so that skidding or slipping is greatly reduced. The fully cured polyurethanes are tough enough to retain the aggregates under normal operating conditions on ramps, near toll stations or in turn lanes. Some formulations can even be modified to produce a Class A Fire Rated system for these Concrete Decks under ASTM E-108, UBC Standard 32-7, UL 790 and NFPA 256. When applied to properly prepared and primed concrete decks, the cured polyurethane coatings form a seamless membrane that is waterproof. These seamless membranes prevent water- soluble salts from entering the steel reinforced concrete decks. Water-soluble salts are the leading cause of corrosion in these decks, so preventing them from entering the decks extends their useful service life, a major benefit to these structures which have very high costs to build and even higher costs to replace. One component, moisture-cured polyurethane greatly reduce the chances of mixing errors; they reduce the costs of transport and staging on the job sites and reduce the labor costs to mix and place them. Aliphatic polyurethane topcoats can be used to provide enhanced protection from UV attacks and degradation as well. And there are even 2-component formulations that are harder once fully cured.
Jaime Molina of Primary Materials Inc. on
August 10, 2016:
For this situation, a non-film-forming sealer shou ...read more For this situation, a non-film-forming sealer should work well. Siloxane type coatings will penetrate the porosity of the concrete andreact chemically with the lime that was released by the cement and is still inside the pore. This will form a polymer inside every pore and effectively seal the surface without changing its coefficient of friction. (It will not make it more slippery.) Since the polymer sealing the concrete resides inside the pores, it is not subject to immediate abrasion and should last some 5 years or more. It may be tinted or not.